Polarizing photochromic articles

Field of the invention

The present invention relates to photochromic articles that include a substrate, a primer layer that includes a first photochromic compound, and a photochromic-dichroic layer over the primer layer that includes a photochromic-dichroic compound, in which the first photochromic compound and the photochromic-dichroic compound are each selected such that the photochromic-dichroic compound has an unactivated state terminal minimum absorbance wavelength that is less than or equal to the unactivated state terminal minimum absorbance wavelength of the underlying first photochromic compound.

Background of the invention

Conventional linearly polarizing elements, such as linearly polarizing lenses for sunglasses and linearly polarizing filters, are typically formed from stretched polymer sheets containing a dichroic material, such as a dichroic dye. Consequently, conventional linearly polarizing elements are static elements having a single, linearly polarizing state. Accordingly, when a conventional linearly polarizing element is exposed to either randomly polarized radiation or reflected radiation of the appropriate wavelength, some percentage of the radiation transmitted through the element will be linearly polarized.

In addition, conventional linearly polarizing elements are typically tinted. Typically, conventional linearly polarizing elements contain a coloring agent and have an absorption spectrum that does not vary in response to actinic radiation. The color of the conventional linearly polarizing element will depend upon the coloring agent used to form the element, and most commonly, is a neutral color (for example, brown or gray). Thus, while conventional linearly polarizing elements are useful in reducing reflected light glare, because of their tint, they are typically not well suited for use under low-light conditions. Further, because conventional linearly polarizing elements have only a single, tinted linearly polarizing state, they are limited in their ability to store or display information.

Conventional linearly polarizing elements are typically formed using sheets of stretched polymer films containing a dichroic material. Correspondingly, while dichroic materials are capable of preferentially absorbing one of two orthogonal plane polarized components of transmitted radiation, if the molecules of the dichroic material are not suitably positioned or arranged, no net linear polarization of transmitted radiation will be achieved. Without intending to be bound by any theory it is believed that due to the random positioning of the molecules of the dichroic material, selective absorption by the individual molecules will cancel each other such that no net or overall linear polarizing effect is achieved. As such, it is typically necessary to position or arrange the molecules of the dichroic material by alignment with another material so as to achieve a net linear polarization.

A common method of aligning the molecules of a dichroic dye involves heating a sheet or layer of polyvinyl alcohol ("PVA") to soften the PVA and then stretching the sheet to orient the PVA polymer chains. Thereafter, the dichroic dye is impregnated into the stretched sheet, and the impregnated dye molecules adopt the orientation of the polymer chains. Resultantly, at least some of the dye molecules become aligned, such that the long axis of each aligned dye molecule is generally parallel to the oriented polymer chains. Alternatively, the dichroic dye can be first impregnated into the PVA sheet, and thereafter the sheet can be heated and stretched as described above to orient the PVA polymer chains and associated dye. In this manner, the molecules of the dichroic dye can be suitably positioned or arranged amongst the oriented polymer chains of the PVA sheet, and a net linear polarization can be correspondingly achieved. As a result, the PVA sheet can be made to linearly polarize transmitted radiation, and correspondingly a linearly polarizing filter can thus be formed.

In contrast to the dichroic elements discussed above, conventional photochromic elements, such as photochromic lenses that are formed using conventional thermally reversible photochromic materials are generally capable of converting from a first state, for example a "clear state," to a second state, for example a "colored state," in response to actinic radiation, and reverting back to the first state in response to thermal energy. Thus, conventional photochromic elements are generally well suited for use in both low-light and bright conditions. Conventional photochromic elements, however, that do not include linearly polarizing filters are generally not capable of linearly polarizing radiation. The absorption ratio of conventional photochromic elements, in either state, is generally less than two. Therefore, conventional photochromic elements are not capable of reducing reflected light glare to the same extent as conventional linearly polarizing elements. In addition, conventional photochromic elements have a limited ability to store or display information.

Photochromic-dichroic compounds and materials have been developed that provide both photochromic properties and dichroic properties, if properly and at least sufficiently aligned. When in a colored or darkened state, such as when exposed to actinic light, photochromic-dichroic compounds, however, typically have a larger percent transmittance than non-polarizing or conventional photochromic compounds at equivalent concentrations and sample thickness. While not intending to be bound by any theory, and based on the evidence at hand, it is believed that the increased percent transmittance of photochromic-dichroic materials in the darkened or colored state is due to the percent transmittance being an average of the two orthogonal plane polarized components of the polarized radiation. A photochromic-dichroic material will more strongly absorb one of the two orthogonal plane polarized components of the incident random radiation, resulting in one of the planes of transmitted polarized light (passing through and out of the sample) having a greater percent transmittance than the other orthogonal plane polarized component. The average of the two orthogonal plane polarized components typically results in an average percent transmittance of greater magnitude. In general, as the linearly polarizing efficiency, which can be quantified in terms of absorption ratio, of photochromic-dichroic compounds increases, the percent transmittance associated therewith also increases.

It would be desirable to develop new polarizing photochromic articles that include photochromic-dichroic compounds, and which provide a combination of linear polarizing properties, and reduced percent transmittance when in a colored or darkened state, such as when exposed to actinic light.

Summary of the invention

In accordance with the present invention, there is provided a photochromic article comprising a substrate and at least two layers thereof including, a primer layer positioned over the substrate, and a photochromic-dichroic layer positioned over the primer layer.

The primer layer comprises a first photochromic compound having a first unactivated state absorbance of greater than 0 at all wavelengths from 340 nm to 380 nm, and a first unactivated state terminal minimum absorbance wavelength of greater than 380 nm.

The photochromic-dichroic layer comprises a photochromic-dichroic compound having a second unactivated state absorbance of greater than 0 over at least a portion of wavelengths from 340 nm to 380 nm, and a second unactivated state terminal minimum absorbance wavelength of greater than 340 nm.

The second unactivated state terminal minimum absorbance wavelength (of the photochromic-dichroic compound) is less than or equal to the first unactivated state terminal minimum absorbance wavelength (of the underlying first photochromic compound).

In accordance with a further embodiment of the present invention, there is provided a photochromic article that includes, a substrate and at least three layers thereover including, a primer layer that is positioned over the substrate, a photochromic-dichroic layer that is positioned over the primer layer, and a topcoat layer that is positioned over the photochromic-dichroic layer.

The primer layer includes a first photochromic compound having a first unactivated state absorbance of greater than 0 at all wavelengths from 340 nm to 380 nm, and a first unactivated state terminal minimum absorbance wavelength of greater than 380 nm.

The photochromic-dichroic layer comprises a photochromic-dichroic compound having a second unactivated state absorbance of greater than 0 over at least a portion of wavelengths from 340 nm to 380 nm, and a second unactivated state terminal minimum absorbance wavelength of greater than 340 nm.

The topcoat layer, of the at least three-layered embodiment, includes an optional ultraviolet light absorber, and a third unactivated state absorbance of greater than 0 over at least a portion of wavelengths from 330 nm to 380 nm, and a third unactivated state terminal minimum absorbance wavelength that is greater than 330 nm.

With the at least three-layered embodiment, the third unactivated state terminal minimum absorbance wavelength (of the second photochromic compound of the topcoat layer) is less than the second unactivated state terminal minimum absorbance wavelength (of the photochromic-dichroic compound of the underlying coating layer), and the second unactivated state terminal minimum absorbance wavelength (of the photochromic-dichroic compound of the coating layer) is less than or equal to the first terminal minimum absorbance wavelength (of the first photochromic compound of the underlying primer layer).

Brief description of the drawings

FIG. 1 is a representative side elevation sectional view of a photochromic article according to the present invention, which includes graphical representations of plots of absorbance vs. wavelength for the first photochromic compound of the primer layer, the photochromic-dichroic compound of the photochromic-dichroic layer, and the second photochromic compound of the topcoat layer;

FIG. 2 is a graphical representation of average delta absorbance as a function of wavelength (over a visible wavelength region after activation with actinic radiation), and depicts two average difference absorption spectra obtained in two orthogonal planes for a photochromic-dichroic layer that includes a photochromic-dichroic compound that can be included in the photochromic articles of the present invention; and

FIG. 3 is a graphical representation of graph 41 of FIG. 1, in which the y-axis range has been changed from 0 to 3.5 (FIG. 1) to 0 to 0.1 (FIG. 3), for purposes of better illustrating the absorbance vs. wavelength plot.

Detailed description of the invention

As used herein, the term "actinic radiation" means electromagnetic radiation that is capable of causing a response in a material, such as, but not limited to, transforming a photochromic material from one form or state to another as will be discussed in further detail herein.

As used herein, the term "photochromic" and similar terms, such as "photochromic compound" means having an absorption spectrum for at least visible radiation that varies in response to absorption of at least actinic radiation. Further, as used herein the term "photochromic material" means any substance that is adapted to display photochromic properties (i.e. adapted to have an absorption spectrum for at least visible radiation that varies in response to absorption of at least actinic radiation) and which includes at least one photochromic compound.

As used herein, the term "photochromic compound" includes thermally reversible photochromic compounds and non-thermally reversible photochromic compounds. The term "thermally reversible photochromic compounds/material's" as used herein means compounds/materials capable of converting from a first state, for example a "clear state," to a second state, for example a "colored state," in response to actinic radiation, and reverting back to the first state in response to thermal energy. The term "non-thermally reversible photochromic compounds/materials" as used herein means compounds/materials capable of converting from a first state, for example a "clear state," to a second state, for example a "colored state," in response to actinic radiation, and reverting back to the first state in response to actinic radiation of substantially the same wavelength(s) as the absorption(s) of the colored state (e.g., discontinuing exposure to such actinic radiation).

As used herein the term "dichroic" means capable of absorbing one of two orthogonal plane polarized components of at least transmitted radiation more strongly than the other.

As used herein, the term "photochromic-dichroic" and similar terms, such as "photochromic-dichroic materials" and "photochromic-dichroic compounds" means materials and compounds that possess and/or provide both photochromic properties (i.e., having an absorption spectrum for at least visible radiation that varies in response to at least actinic radiation), and dichroic properties (i.e., capable of absorbing one of two orthogonal plane polarized components of at least transmitted radiation more strongly than the other).

As used herein the term "absorption ratio" refers to the ratio of the absorbance of radiation linearly polarized in a first plane to the absorbance of the same wavelength radiation linearly polarized in a plane orthogonal to the first plane, in which the first plane is taken as the plane with the highest absorbance.

As used herein to modify the term "state," the terms "first" and "second" are not intended to refer to any particular order or chronology, but instead refer to two different conditions or properties. For purposes of non-limiting illustration, the first state and the second state of the photochromic-dichroic compound of the photochromic-dichroic layer can differ with respect to at least one optical property, such as but not limited to the absorption or linearly polarization of visible and/or UV radiation. Thus, according to various non-limiting embodiments disclosed herein, the photochromic-dichroic compound of the photochromic-dichroic layer can have a different absorption spectrum in each of the first and second state. For example, while not limiting herein, the photochromic-dichroic compound of the photochromic-dichroic layer can be clear in the first state and colored in the second state. Alternatively, the photochromic-dichroic compound of the photochromic-dichroic layer can have a first color in the first state and a second color in the second state. Further, as discussed below in more detail, the photochromic-dichroic compound of the photochromic-dichroic layer can be non-linearly polarizing (or "non-polarizing") in the first state, and linearly polarizing in the second state.

As used herein the term "optical" means pertaining to or associated with light and/or vision. For example, according to various non-limiting embodiments disclosed herein, the optical article or element or device can be chosen from ophthalmic articles, elements and devices, display articles, elements and devices, windows, mirrors, and active and passive liquid crystal cell articles, elements and devices.

As used herein the term "ophthalmic" means pertaining to or associated with the eye and vision. Non-limiting examples of ophthalmic articles or elements include corrective and non-corrective lenses, including single vision or multi-vision lenses, which may be either segmented or non-segmented multi-vision lenses (such as, but not limited to, bifocal lenses, trifocal lenses and progressive lenses), as well as other elements used to correct, protect, or enhance (cosmetically or otherwise) vision, including without limitation, contact lenses, intra-ocular lenses, magnifying lenses, and protective lenses or visors.

As used herein the term "ophthalmic substrate" means lenses, partially formed lenses, and lens blanks.

As used herein the term "display" means the visible or machine-readable representation of information in words, numbers, symbols, designs or drawings. Non-limiting examples of display articles, elements and devices include screens, monitors, and security elements, such as security marks.

As used herein the term "window" means an aperture adapted to permit the transmission of radiation therethrough. Non-limiting examples of windows include automotive and aircraft transparencies, filters, shutters, and optical switches.

As used herein the term "mirror" means a surface that specularly reflects a large or substantial fraction of incident light.

As used herein the term "liquid crystal cell" refers to a structure containing a liquid crystal material that is capable of being ordered. Active liquid crystal cells are cells in which the liquid crystal material is capable of being reversibly and controllably switched or converted between ordered and disordered states, or between two ordered states by the application of an external force, such as electric or magnetic fields. Passive liquid crystal cells are cells in which the liquid crystal material maintains an ordered state. A non-limiting example of an active liquid crystal cell element or device is a liquid crystal display.

As used herein the term "coating" means a supported film derived from a flowable composition, which may or may not have a uniform thickness, and specifically excludes polymeric sheets. The primer layer, the photochromic-dichroic layer and the optional topcoat layer of the photochromic articles of the present invention can, in some embodiments, each independently be a coating.

As used herein the term "sheet" means a pre-formed film having a generally uniform thickness and capable of self-support.

As used herein the term "connected to" means in direct contact with an object or indirect contact with an object through one or more other structures or materials, at least one of which is in direct contact with the object. For purposes of non-limiting illustration, the primer layer, for example, can be in direct contact (e.g., abutting contact) with at least a portion of the substrate or it can be in indirect contact with at least a portion of the substrate through one or more other interposed structures or materials, such as a monomolecular layer of a coupling or adhesive agent. For example, although not limiting herein, the primer layer can be in contact with one or more other interposed coatings, polymer sheets or combinations thereof, at least one of which is in direct contact with at least a portion of the substrate.

As used herein, the term "photosensitive material" means materials that physically or chemically respond to electromagnetic radiation, including, but not limited to, phosphorescent materials and fluorescent materials.

As used herein, the term "non-photosensitive materials" means materials that do not physically or chemically respond to electromagnetic radiation, including, but not limited to, static dyes.

As used herein, molecular weight values of polymers, such as weight average molecular weights (Mw) and number average molecular weights (Mn), are determined by gel permeation chromatography using appropriate standards, such as polystyrene standards.

As used herein, polydispersity index (PDI) values represent a ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the polymer (i.e., Mw/Mn).

As used herein, the term "polymer" means homopolymers (e.g., prepared from a single monomer species), copolymers (e.g., prepared from at least two monomer species), and graft polymers.

As used herein, the term "(meth)acrylate" and similar terms, such as "(meth)acrylic acid ester" means methacrylates and/or acrylates. As used herein, the term "(meth)acrylic acid" means methacrylic acid and/or acrylic acid.

Unless otherwise indicated, all ranges or ratios disclosed herein are to be understood to encompass any and all subranges or subratios subsumed therein. For example, a stated range or ratio of "1 to 10" should be considered to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges or subratios beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less, such as but not limited to, 1 to 6.1, 3.5 to 7.8, and 5.5 to 10.

As used herein and in the claims, unless otherwise indicated, left-to-right representations of linking groups, such as divalent linking groups, are inclusive of other appropriate orientations, such as, but not limited to, right-to-left orientations. For purposes of non-limiting illustration, the left-to-right representation of the divalent linking group

##STR00001## or equivalently --C(O)O--, is inclusive of the right-to-left representation thereof,

##STR00002## or equivalently --O(O)C-- or --OC(O)--.

As used herein, the articles "a," "an," and "the" include plural referents unless otherwise expressly and unequivocally limited to one referent.

As used herein, the term "a first photochromic compound" means at least one first photochromic compound. When two or more first photochromic compounds are present, they together have and provide a (e.g., an average) first unactivated state peak absorbance wavelength, a (e.g., an average) first unactivated state absorbance of greater than 0 over a particular wavelength range, a (e.g., an average) first unactivated state terminal minimum absorbance wavelength, and a (e.g., an average) first unactivated state initial minimum absorbance wavelength.

As used herein, the term "a photochromic-dichroic compound" means at least one photochromic-dichroic compound. When two or more photochromic-dichroic compounds are present, they together have and provide a (e.g., an average) second unactivated state peak absorbance wavelength, a (e.g., an average) second unactivated state absorbance of greater than 0 over a particular wavelength range, a (e.g., an average) second unactivated state terminal minimum absorbance wavelength, and a (e.g., an average) second unactivated state initial minimum absorbance wavelength.

As used herein, the term "a second photochromic compound" means at least one second photochromic compound. When two or more second photochromic compounds are present, they together have and provide a (e.g., an average) third unactivated state peak absorbance, a (e.g., an average) third unactivated state absorbance wavelength of greater than 0 over a particular wavelength range, a (e.g., an average) third unactivated state terminal minimum absorbance wavelength, and a (e.g., an average) third unactivated state initial minimum absorbance wavelength.

As used herein, the term "unactivated state" with regard to photochromic compounds, such as the first photochromic compound, the photochromic-dichroic compound and the second photochromic compound, means the photochromic compound has been exposed to actinic radiation having sufficient energy to result in the photochromic compound having or producing: (i) measurable absorbance at wavelengths of greater than or equal to 330 nm and less than or equal to 450 nm, such as less than or equal to 430 nm or less than or equal to 410 nm; and (ii) minimal or substantially no measurable absorbance at wavelengths of greater than 450 nm.

As used herein, the term "activated state" with regard to photochromic compounds, such as the first photochromic compound, the photochromic-dichroic compound and the second photochromic compound, and photochromic articles, means the photochromic compound and/or photochromic article has been exposed to actinic radiation having sufficient energy to result in the photochromic compound and/or photochromic article having or producing: (i) measurable absorbance at wavelengths of greater than or equal to 330 nm and less than or equal to 450 nm, such as less than or equal to 430 nm or less than or equal to 410 nm; and (ii) measurable absorbance at wavelengths of greater than 450 nm.

As used herein, the term "a first unactivated state absorbance of greater than 0" over a certain wavelength range, such as "over all wavelengths from 340 nm to 380 nm" means the first photochromic compound has an unactivated state absorbance of greater than 0 over a certain wavelength range, such as at all wavelengths from 340 nm to 380 nm.

As used herein, the term "a first unactivated state peak absorbance wavelength" means the wavelength at which the first photochromic compound (of the primer layer), in an unactivated state, has a peak (or maximum) absorbance. The first unactivated state peak absorbance wavelength typically resides between 340 nm and 380 nm.

As used herein, the term "a first unactivated state terminal minimum absorbance wavelength" means the wavelength at which the first photochromic compound (of the primer layer), in an unactivated state, has a terminal (or upper) minimum absorbance. The first unactivated state terminal minimum absorbance wavelength is at higher wavelength than the first unactivated state peak absorbance wavelength.

As used herein, the term "a first unactivated state initial minimum absorbance wavelength" means the wavelength at which the first photochromic compound (of the primer layer), in an unactivated state, has an initial (or lower) minimum absorbance. The first unactivated state minimum absorbance wavelength is at lower wavelength than the first unactivated state peak absorbance wavelength and the first unactivated state terminal minimum absorbance wavelength.

As used herein, the term "a second unactivated state absorbance of greater than 0" over a certain wavelength range, such as "over at least a portion of wavelengths from 340 nm to 380 nm" means the photochromic-dichroic has an unactivated state absorbance of greater than 0 over a certain wavelength range, such as over at least a portion of wavelengths from 340 nm to 380 nm, such as from 340 nm to 370 nm, or from 350 nm to 380 nm, or from 340 nm to 380 nm.

As used herein, the term "over at least a portion of wavelengths from x nm to y nm" with regard to an unactivated state absorbance of greater than 0, means over at least a portion of consecutive wavelengths within the recited range, inclusive of the recited upper and lower wavelength values.

As used herein, the term "a second unactivated state peak absorbance wavelength" means the wavelength at which the photochromic-dichroic compound (of the coating layer, or photochromic-dichroic coating layer), in an unactivated state, has a peak (or maximum) absorbance. The second unactivated state peak absorbance wavelength typically resides between 340 nm and 380 nm.

As used herein, the term "a second unactivated state terminal minimum absorbance wavelength" means the wavelength at which the photochromic-dichroic compound (of the coating layer, or photochromic-dichroic coating layer), in an unactivated state, has a terminal (or upper) minimum absorbance. The second unactivated state terminal minimum absorbance wavelength is at higher wavelength than the second unactivated state peak absorbance wavelength.

As used herein, the term "a second unactivated state initial minimum absorbance wavelength" means the wavelength at which the photochromic-dichroic compound (of the photochromic-dichroic layer), in an unactivated state, has an initial (or lower) minimum absorbance. The second unactivated state minimum absorbance wavelength is at lower wavelength than the second unactivated state peak absorbance wavelength and the second unactivated state terminal minimum absorbance wavelength.

As used herein, the term "a third unactivated state absorbance of greater than 0" over a certain wavelength range, such as "over a portion of wavelengths from 330 nm to 380 nm" means the second photochromic compound has an unactivated state absorbance of greater than 0 over a certain wavelength range, such as over at least a portion of wavelengths from 330 nm to 380 nm, such as from 330 nm to 370 nm, or from 340 nm to 380 nm.

As used herein, the term "a third unactivated state peak absorbance wavelength" means the wavelength at which the second photochromic compound (of the topcoat layer), in an unactivated state, has a peak (or maximum) absorbance. The third unactivated state peak absorbance wavelength typically resides between 330 nm and 380 nm.

As used herein, the term "a third unactivated state terminal minimum absorbance wavelength" means the wavelength at which the second photochromic compound (of the topcoat layer), in an unactivated state, has a terminal (or upper) minimum absorbance. The third unactivated state terminal minimum absorbance wavelength is at higher wavelength than the third unactivated state peak absorbance wavelength.

As used herein, the term "a third unactivated state initial minimum absorbance wavelength" means the wavelength at which the second photochromic compound (of the topcoat layer), in an unactivated state, has an initial (or lower) minimum absorbance. The third unactivated state minimum absorbance wavelength is at lower wavelength than the third unactivated state peak absorbance wavelength and the third unactivated state terminal minimum absorbance wavelength.

The unactivated state initial minimum absorbance wavelength values, such as the first, second and/or third unactivated state initial minimum absorbance wavelength values, can each be affected by the analytical method and equipment employed, and the substrate and/or the matrix, such as the coating matrix, in which the particular photochromic compound resides (which is referred herein as a "USIMAWV affect"). The USIMAWV affect can be more pronounced when the unactivated state initial minimum absorbance wavelength value is less than 360 nm. The USIMAWV affect can be additive or subtractive, resulting in higher or lower unactivated state initial minimum absorbance wavelength values. Alternatively or additionally, the USIMAWV affect can result in unactivated state initial minimum absorbance wavelength values having negative absorbance values. Still further, the USIMAWV affect can result in positive and/or negative absorbance spikes, in particular at wavelength values less than 360 nm. While not intending to be bound by any theory, it is believed that, in the case of organic polymer substrates and organic polymer coatings, the USIMAWV affect is due, at least in part, to the presence of aromatic rings in the substrate and/or the coating matrix, coupled with instrument reference subtraction. With some embodiments, when the substrate is quartz, the USIMAWV affect can be minimized. Since substrates and coatings composed of organic polymer materials, and instrument reference subtraction were used, it is believed that the first, second and third unactivated state initial minimum absorbance wavelength values (65, 68 and 71) as described in further detail herein with reference to FIGS. 1 and 3, may have been subject to the USIMAWV affect.

As used herein, and unless otherwise indicated, "percent transmittance" was determined using an ULTRASCAN PRO spectrometer obtained commercially from HunterLab, in accordance with instructions provided in the spectrometer user manual.

As used herein the term "linearly polarize" means to confine the vibrations of the electric vector of electromagnetic waves, such as light waves, to one direction or plane.

Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be under stood as modified in all instances by the term "about."

As used herein, spatial or directional terms, such as "left", "right", "inner", "outer", "above", "below", and the like, relate to the invention as it is depicted in the drawing figures. However, it is to be understood that the invention can assume various alternative orientations and, accordingly, such terms are not to be considered as limiting.

As used herein, the terms "formed over," "deposited over," "provided over," "applied over," residing over," or "positioned over," mean formed, deposited, provided, applied, residing, or positioned on but not necessarily in direct (or abutting) contact with the underlying element, or surface of the underlying element. For example, a layer "positioned over" a substrate does not preclude the presence of one or more other layers, coatings, or films of the same or different composition located between the positioned or formed layer and the substrate.

All documents, such as but not limited to issued patents and patent applications, referred to herein, and unless otherwise indicated, are to be considered to be "incorporated by reference" in their entirety.

With reference to FIG. 1, and for purposes of non-limiting illustration, a photochromic article 2 according to the present invention is depicted. Photochromic article 2 includes a substrate 11 having a first surface 12 and a second surface 13, in which the first 12 and second 13 surfaces are opposed to each other. First surface 12 of substrate 11 faces incident actinic radiation depicted by arrow 15. Photochromic article 2 further includes a primer layer 14 over (e.g., abutting) substrate 11 and in particular over (e.g., abutting) first surface 12 of substrate 11. Photochromic article 2 further includes a coating layer 17 (which is also referred to herein as a photochromic-dichroic layer 17) over primer layer 14, and an optional topcoat layer 20 over photochromic-dichroic layer 17. Photochromic article 2 of FIG. 1 includes other optional layers, which will be described further herein.

Primer layer 14 includes a first photochromic compound having absorbance properties represented by graph 23, which is a representative plot of absorbance vs. wavelength for the first photochromic compound in an unactivated state. More particularly, graph 23 is obtained from analysis of primer 14 applied to substrate 11 in the absence of other underlying or overlying layers. With reference to graph 23 of FIG. 1, the first photochromic compound has a first unactivated state peak absorbance wavelength 26, a first unactivated state terminal minimum absorbance wavelength 29, and a first unactivated state initial minimum absorbance wavelength 65 that is not depicted in graph 23, but which is less than 340 nm. The first unactivated state terminal minimum absorbance wavelength 29 of the first photochromic compound is at higher wavelength than the first unactivated state peak absorbance wavelength 26 thereof. The first unactivated state initial minimum absorbance wavelength 65 is at lower wavelength than the first unactivated state peak absorbance wavelength 26.

For purposes of non-limiting illustration, and with further reference to graph 23 of FIG. 1, the first unactivated state peak absorbance wavelength 26 of the first photochromic compound of primer layer 14 is 355 nm, the first unactivated state terminal minimum absorbance wavelength 29 is 425 nm, and the first unactivated state initial minimum absorbance wavelength 65 is 333 nm (not depicted).

The unactivated state terminal minimum absorbance wavelength values of the photochromic compounds and photochromic-dichroic compounds of the photochromic articles of the present invention can be determined in accordance with art-recognized methods. In some embodiments, the unactivated state absorbance of the photochromic or photochromic-dichroic compounds clearly drops to zero, and the wavelength at the zero point is recorded. In other embodiments, the unactivated state absorbance of the photochromic or photochromic-dichroic compound drops to a minimum plateau value, which may not reach a measured absorbance of zero. In the case of a minimum plateau value, the unactivated state terminal minimum absorbance wavelength values are typically estimated. For purposes of non-limiting illustration and with reference to FIG. 3, the third unactivated state terminal minimum absorbance wavelength 47 is estimated by extending a line, represented by dashed line 62, from a linear portion 56 of the absorbance vs. wavelength trace that resides to the left of (i.e., at lower wavelength relative to) the inflection point 59 of the trace. The point at which the extended line 62 intersects the x-axis is recorded as the third unactivated state terminal minimum absorbance wavelength value. The estimated unactivated state terminal minimum absorbance wavelength points and values as described can be determined by calculation (typically with the use of a computer graphing program) or manually (e.g., using a ruler). Unless otherwise indicated, the estimated unactivated state terminal minimum absorbance wavelength points and values depicted and discussed with reference to FIG. 1 were determined manually.

The unactivated state initial minimum absorbance wavelength values can be estimated in accordance with a method similar to that described with regard to the terminal minimum absorbance wavelength values. A line is extended from a linear portion of the absorbance vs. wavelength trace that resides to the right of (i.e., at higher wavelength relative to) the lower inflection point of the trace. With some embodiments, the unactivated state initial minimum absorbance clearly occurs at a value of zero absorbance along the x-axis, and as such does not have to be estimated.

Photochromic-dichroic layer 17 of photochromic article 2 includes a photochromic-dichroic compound having absorbance properties represented by graph 32, which is a plot of absorbance vs. wavelength for the photochromic-dichroic compound. More particularly, graph 32 is obtained from analysis of photochromic-dichroic layer 17 applied to substrate 11 in the absence of other underlying or overlying layers. With reference to graph 32 of FIG. 1, the photochromic-dichroic compound has a second unactivated state peak absorbance wavelength 35, a second unactivated state terminal minimum absorbance wavelength 38, and a second unactivated state initial minimum absorbance 68. The unactivated state second terminal minimum absorbance wavelength 38 of the photochromic-dichroic compound is at higher wavelength than the second peak absorbance wavelength 35 thereof. The unactivated state second initial minimum absorbance wavelength 68 of the photochromic-dichroic compound is at lower wavelength than the second peak absorbance wavelength 35.

For purposes of non-limiting illustration, and with further reference to graph 32 of FIG. 1, the second unactivated state peak absorbance wavelength 35 of the photochromic-dichroic compound of photochromic-dichroic layer 17 is 360 nm, the second unactivated state terminal minimum absorbance wavelength 38 is 417 nm, and the second unactivated state initial minimum absorbance wavelength 68 is 342 nm.

The description continues in the full USPTO document.